1. Field of the Invention
The present invention relates to a manual focusing mechanism of an imaging apparatus, and also relates to the imaging apparatus itself.
2. Description of Related Art
In a manual focusing mechanism of an imaging apparatus (e.g., a camera), it is normal to attain an in-focus state by moving a focusing lens group along the optical axis direction thereof in a stepless manner via a manual rotational operation of a focusing ring. However, Japanese Unexamined Patent Publication No. 2005-62385 teaches a focusing mechanism for highly specialized purposes in which a focusing lens group is moved stepwise along the optical axis direction thereof.
Manual focusing is usually carried out by rotating a manual focusing ring while visually confirming the actual focus state; however, it is very difficult to discern the extent by which the manual focusing ring should be rotated under conditions where the focus state cannot be visually confirmed in real-time. For example, in recent years, many surveillance cameras have been using transparent covers to cover the exterior of the camera. In such cameras, in which the focal length of the camera lens thereof is adjusted and then set (fixed) at the adjusted focal length, sometimes the focal length deviates from the in-focus position (state) due to the transparent cover being subsequently mounted and changing the optical conditions. It has proven difficult, requiring expert skill, to adjust the focal length of the camera lens in order to offset such focal-length deviation before mounting the transparent cover with such a conventional manual focusing mechanism.